[IRSim] Adding wrapper pass for IRSimilarityIdentfier

This introduces an analysis pass that wraps IRSimilarityIdentifier,
and adds a printer pass to examine in what function similarities are
being found.

Test for what the printer pass can find are in
test/Analysis/IRSimilarityIdentifier.

Reviewed by: paquette, jroelofs

Differential Revision: https://reviews.llvm.org/D86973